“…A number of papers are devoted to theoretical studies of the formation of such structures. Their formation is associated with perturbations in the disks caused by the motion of the forming planets (e.g., Ruge et al 2013;Dong et al 2015;van der Marel et al 2015;Jin et al 2016;Demidova & Shevchenko 2016;Dong et al 2018), the development of various kinds of instabilities in the disks (e.g., Johansen et al 2009;Takahashi & Inutsuka 2014;Bai & Stone 2014;Birnstiel et al 2015;Banzatti et al 2015;Zhang et al 2015;Okuzumi et al 2016;Dullemond & Penzlin 2018), a large-scale vertical magnetic field (Suriano et al 2018), or with the destruction of large bodies in collision (Demidova & Grinin 2019;Nayakshin et al 2020). In all of these papers, the source of disturbance is in the disk itself.…”